Oxidation and Decarboxylation. A Reaction Sequence for the Study of Aromatic Structural Elements in Pocahontas No. 3 Coal

Abstract

Oxygen in basic solution has been used to oxidize Pocahontas No. 3 coal to a mixture of aromatic carboxylic acids, and copper(I) oxide in N-methylpyrrolidinone-quinoline has been used to decarboxylate the acids to provide a mixture of hydrocarbons. Most pendant alkyl groups have been removed in this sequence and the product distribution is much less complex than the product distributions that are obtained in direct oxidation reactions or in the analysis of coal liquids and extracts. Approximately 25% of the aromatic carbon atoms are retained in the products. The structures of these compounds have been investigated by gas chromatography-mass spectrometry and by high-resolution and laser desorption mass spectrometry. Approximately 150 compounds were detected in the GCMS experiments including a broad array of bi-, ter-, and quateraryls, fluorene and fluoranthene derivatives, polycyclic aromatic hydrocarbons with four, five, and six rings, dibenzo-and dinaphthofurans, and dibenzo-and dinaphthothiophenes. High-resolution mass spectrometry provided additional evidence concerning the principal products and extended the mass range to approximately 400 Da. Laser desorption work revealed that even larger molecules were present in the reaction products with distinct signals at 550 Da and definite intensity extending to 1200 Da. These results are compatible with many other results that have been obtained in the past decade and strongly infer that the relatively high-ranking Pocahontas No. 3 coal has many large, condensed, aromatic clusters that are methylated and connected through biaryl and heterocyclic linkages.

Use of molecular modeling to determine the interaction and competition of gases within coal for carbon dioxide sequestration

“…3 coal was generated. This model was constructed based on a the review data of Stock and Muntean 1 , oxidation and decarboxylation data for aromatic clustersize frequency of Stock and Obeng 2 , and the combination of Laser Desorption Mass Spectrometry data with HRTEM 3 , enabled the inclusion of a molecular weight distribution. The model contains 21,931 atoms, with a molecular mass of 174,873 amu, and an average molecular weight of 714 amu, with 201 structural components.…”

“…3 was constructed in a similar manner to that already discussed 9 . Here the bulk data were obtained from the literature review of Stock and Muntean 1 , and the oxidation decarboxylation data to determined aromatic cluster-size relative abundance 2 , along with the molecular weight distribution determined from the combination of HRTEM and laser desorption mass spectrometry (LDMS) data. The details of the elucidation of the molecular weight distribution using the complimentary HRTEM and LDMS data are available elsewhere 3 .…”

A novel process for the production of aromatic hydrocarbons from brown coal in water medium by hydrothermal oxidation and catalytic hydrothermal decarboxylation

“…A combination method of oxidation and decarboxylation is a feasible approach to convert brown coal to aromatic hydrocarbons with no use of hydrogen or hydrogen donors under mild conditions [3][4][5][6][7][8]. In the oxidation process, aromatic carboxylic acids are obtained from coal, and then during the decarboxylation process, carboxylic functional groups in aromatic carboxylic acids are removed to form aromatic hydrocarbons.…”

Phenyl derivatives of polycyclic aromatic compounds as indicators of hydrothermal activity in the Silurian black siliceous shales of the Bardzkie Mountains, Poland

“…These authors identified numerous groups of phenyl-and naphthyl-PAC derivatives, including: phenylnaphthalenes, terphenyls, phenylphenanthrenes, phenyl-and diphenylbenzo [b]thiophenes, phenyldibenzothiophenes, phenylnaphtho[b]thiophenes, naphthylbenzo [b]thiophenes, phenyldibenzofurans, and tentatively identified phenyltriphenylenes, quater-, quinque-and sexiphenyls. Based on the knowledge about the natural occurrence of PhPACs and their formation processes during oxidative pyrolysis of coal and coal-derived materials (Marynowski et al, 2004;Meyer zu Reckendorf, 1997, 2000, as well as chemical decarboxylation and oxidation of hard coals (Stock and Obeng, 1997), it is believed that their origin is connected with freeradical OM phenylation reactions. Moreover, ionic versus free-radical phenylation experiments confirmed the formation of these compound groups according to the latter process (Rospondek et al, 2007(Rospondek et al, , 2009).…”